In North America, and many other parts of the world, mobile telecommunication networks are characterized by different standards such as TDMA, CDMA, GSM, iDEN and many variants thereof, such as 2G (Second Generation Networks) and 3G (Third Generation Networks). The standards typically specify the radio interface characteristics, equipment details and associated number schemes, applicable communication protocols including the associated message definitions and characteristics of inter-connecting networks. While some of the concepts are common among these disparate standards, the commonality of the concepts is not sufficient to make devices belonging to one network talk to devices belonging to another network for wireless messaging needs.
A telecommunication network supports many services. Primary among them are voice calls and messaging. Aspects of the present invention primarily concern messaging and, therefore, this description concentrates on expanding upon the state of messaging standards.
The wireless messaging revolution started primarily with the GSM standard with the introduction of Short Message Service (SMS). An SMS message can have a maximum of 160 characters (140 octets) and is used for a number of applications including person to person messaging, binary content such as ring tones, person to application messaging and a number of other uses. Almost all other standards such as ANSI TDMA and CDMA wireless networks also have implemented an equivalent form of short message support within their networks. A notable exception is iDEN, which implemented a packet data network and while messaging is supported, it does not have anything equivalent to short messaging.
There are other forms of messaging such as EMAIL, WAP and more recently Multimedia messages (MMS) supported by many of the networks. In some cases, one form of messaging is carried over the bearers of other forms of messaging. For example, an EMAIL message could be implemented with SMS as a bearer service.
In general, it is not easily possible to exchange messages across different networks supporting different wireless standards. SMS messaging has become very popular in Europe and other parts of the world due to implementation of the GSM standard in many networks, which makes it possible to exchange SMS messages easily across the networks. In the case of ANSI TIA/EIA 41 standards, such an exchange has not been possible until aspects of the present invention were put in place in North America in the year 2001.
The exchange of messages across different networks is further complicated by roaming, number portability, quality of service, “spam”, and billing requirements. Due to its very nature, mobile networks permit roaming of subscriber units within the network and other networks implementing compatible standards, provided a business arrangement between the effected networks exists. In order to deliver a message to a mobile unit, it is necessary to find its current location and associated gateway and interface address.
One of the features of number portability is the ability to port a number from one service provider to another. Number portability poses problems with the delivery of messages when relatively static routing tables are used. A similar but independent problem arises out of “number range contamination”. In North America, for example, messages and calls are routed to networks using what is known as NPA/NXX ranges. This methodology refers to routing of calls using the first 6 digits of the telephone number (TN) in the North American Number Plan (NANP). Traditionally, a set of number ranges segmented by NPA/NXX are assigned to service providers.
Recently, in United States, a change has been made in telephone number range assignments to service providers. Instead of the usual 6 digit number ranges, the assignments are made, now, using 7 digit ranges. However, during the reassignment, certain numbers in a range may be, what is termed as, “contaminated,” where a small percentage of numbers may belong to one service provider, even though the range as a whole is owned by another service provider.
In addition to the contaminated and ported number issues mentioned above, there are a number of other inter-connectivity issues that may need to be addressed for flexible and reliable message bridging across different networks. For example, a source and destination network (with respect to a message going between subscribers of those two networks) may be inter-connected by more than one Intermediate network. The routing tables and associated methodologies must account for this multi-hop connection. A destination network may be accessible only through a designated service provider to the network. For example a SS7 service provider may have exclusive access to a carrier's network and the message must be routed through such a connection. There may be multiple types of connections to a network to reach the same mobile subscriber. Further, there may be multiple instances of a particular type of connection to a network to reach the same mobile subscribers.
In addition, there might be varying levels of Quality of Service for multiple connections to the same network.
To summarize, the following are many of the challenges that need to be addressed for successful and reliable exchanging messages between disparate wireless networks:                Protocol Conversion—ability to account for protocol differences        Transmission network support—ability to connect with the right kind of transmission network        Inter-Domain or Inter-network Addressing Conversion—ability to perform address translation, as necessary        Dynamic Routing Lookup—ability to resolve for accurate and timely routing information        Message Transformation—ability to transform messages based on business and technical needs        Storage and re-transmittal—ability to store and forward based on business and technical needs        Recording of transmission events for billing and other uses—ability to record the message transmission events        Management channel support—ability to manage message transmission        Anti-spam, Authentication and other centralized value add services—ability to provide network protection.        Lateral transmission to other Intermediary networks—ability to interface with multiple networks        Transaction support—ability to reliably transact a message delivery attempt        Quality of Service—ability to support varying quality levels in providing service        
The network and system explained in this invention solves many of the above problems uniquely.
Interchanging signaling and messages between networks for peer to peer calls, messaging and roaming has been addressed in the prior art before by standards bodies, published papers and patents. Patent number WO 97/20442, for example, identifies a mechanism to exchange Short Message Service (SMS) between different networks by enabling the message center of a cellular network with the functionality of identifying target network, addressing mechanism and format. In particular, the patent describes a system that allows messages to be delivered to a conventional telephone network using facsimile message format transmission and wide or local area network using email message transmission. This system, however, specifically requires the sender of the message to identify destination network, protocol and the address of the recipient device within the network. Moreover it assumes that the message center of the cellular network is directly connected to the destination network by PSTN, LAN or WAN network, which is not necessarily the case in many practical networks.
Another system, described in DE 295 11 856 U1, provides a slightly alternate mechanism by way of use of a central switching device. A designated network specific device receives a message, stores the message, re-formats the message to suit an exchange format, and forwards the message to a central switching device. The central switch then routes the message to another device connected to the destination network. This system assumes a monolithic central switching device which could be a single failure point and doesn't offer much flexibility in dealing with many complexities (as are addressed here-in) of inter-connecting a plurality of networks. Moreover, a central monolithic switching device may become a performance bottleneck.
Another known technique proposes a plurality of intermediate switching architectures to overcome the above mentioned drawbacks.
WO 02/15603 A2 describes a centralized computer system or a computer program connected to a plurality of networks directly for delivering messages between networks and applications using a centralized routing database.
All the above systems and techniques take a relatively simplistic view of bridging messaging structures between various networks. They assume simplistic routing rules without considering many practical peculiarities of network interconnections. For example, in North America (and many countries) number pooling, contaminated ranges and portability make it difficult to correctly identify the destination carrier. Sometimes the messages coming from a network may have to be delivered back to the same network, after performing certain message transformations or route lookups. Due to wireless number portability, the numbers may be ported frequently, which makes it difficult to correctly resolve the destination network identity based on the address provided by originating subscriber. None of the patents cited above addresses these scenarios.
Also, the above patents do not address the issue of roaming subscribers. Nor do they address the possibility of a plurality of connections or links, possibly operating different protocols, to the same destination network and mechanisms to choose a particular connection in an optimized way. In addition, multiple protocol addresses assigned to the same subscriber unit is possible within the same network in the real world (such as an email address and phone number to the same mobile unit), which again does not find any mention in any of the above patents. Security, authentication, billing, error handling, reporting and many other value-add functions that are critically important for message delivery in the practical world are not mentioned in the above cited inventions.
In addition, the cited patents do not explicitly refer to delivery of messages using SS7 networks directly which is the preferred network protocol used by almost all the telecommunication networks for delivering messages. SS7 is the core network inter-connecting network elements of wireless networks currently.
Therefore, realization of any practically relevant message delivery system based on the above patents falls short of a reliable message delivery mechanism between networks because of the cited reasons.
WO 02/05580 A1, however, clearly addresses delivery of SMS messages between PLMNs (Public Land Mobile Network) using the traditional SS7 network approach involving Switching Centers, Message Service Centers, Home Location Registers and the like. However, the described system strictly deals with bridging two different SS7 networks through an inter-working message center and does not address other forms of interconnection such as IP networks. In addition, this invention deals with end to end message transmission using MAP signaling messages, wherein, particular message sequences are translated into the format of destination network. The approach proposed by this system works only for SMS messages and doesn't perform any kind of message transformations. For example, if the destination network doesn't open up the SS7 network for Intermediary for message delivery, the system fails to provide a solution.